Method for making an optical fiber device from a 3d printed preform body and related structures

ABSTRACT

A method for making an optical fiber device may include using a three-dimensional (3D) printer to generate a preform body including an optical material. The preform body may have a 3D pattern of voids therein defining a 3D lattice. The method may further include drawing the preform body to form the optical fiber device.

TECHNICAL FIELD

The present invention relates to the field of communications, and moreparticularly, to optical fibers and related methods.

BACKGROUND

Fiber-optic communication utilizes optical fibers to transportcommunication signals which have been modulated to various wavelengthsof light. This allows for transmission over longer distances and withhigher bandwidths than conventional wire cables, because optical fibershave less signal loss than conventional cables.

Nevertheless, the fabrication of photonic crystal fibers is generallymore difficult than traditional optical fibers. Typically, 10⁵ to 10⁶capillary tubes and solid rods are manually assembled into a preform.The preform is then heated and drawn or pulled into the final opticalfiber. This process is typically labor intensive and costly. Moreover,it may be difficult to draw such preforms without inducing defects,which may make the resulting fibers fragile and unsuitable for use atcertain optical wavelengths.

Various alternative approaches have been attempted to create opticalfibers. In a paper entitled “Complex air-structured optical fiber drawnfrom a 3D-printed preform” by Cook et al. (Optics Letters, Vol. 40,Issue 17, pp. 3966-3969 (2015)), an alternative approach to makingstructured fibers is discussed which utilizes a 3D printer to design andprint a structured preform that is then drawn to fiber. An FDM printingmethod was used to print a preform using a transparent thermosettingpolymer that is subsequently drawn to fiber. The preform fiber geometrywas a solid core surrounded by 6 air holes. A commercially available 3Dprinting filament was used consisting of a polystyrene mixturecontaining styrene-butadiene-copolymer and polystyrene.

Despite the existence of such approaches, new techniques for creatingoptical fibers may be desirable to provide improved robustness,longevity, as well as operation at different optical wavelengths.

SUMMARY

A method for making an optical fiber device may include using athree-dimensional (3D) printer to generate a preform body including anoptical material. The preform body may have a 3D pattern of voidstherein defining a 3D lattice. The method may further include drawingthe preform body to form the optical fiber device.

More particularly, the preform body may include a plurality of strands.By way of example, the strands may be helical strands. In one exampleembodiment, the strands may be counter-rotating, helical strands. Inaccordance with another example, the strands may be intersecting,counter-rotating, helical strands.

At least some of the voids may open outwardly along a side of thepreform body. Furthermore, drawing may include drawing the preform bodywhile retaining the 3D pattern of voids therein. In addition, the methodmay also include coating at least a portion of the preform body with adifferent material prior to drawing. In accordance with another example,the method may further include electroplating at least a portion of thepreform body prior to drawing. By way of example, at least a portion ofthe preform body may be coated with gold.

In one example implementation, the preform body may include a pluralityof strands, and at least one of the plurality of strands may comprise ametal. As such, the method may further include passing an electricalcurrent through the at least one metal strand during drawing. By way ofexample, the metal may comprise tungsten.

In accordance with another example aspect, drawing may include drawingthe preform body in a direction offset with respect to an optical axisof the optical fiber device. In another example, drawing may includedrawing the preform body in axial and radial directions with respect toan optical axis of the optical fiber device. By way of example, thepreform body may include at least one of silica, silicon carbide, andaluminum oxide.

A preform body is also provided. The preform body may include anelongate body to be drawn into a fiber optic device and including anoptical material. Furthermore, the elongate body may have a 3D patternof voids therein defining a 3D lattice.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a 3D-printed preform body for use informing an optical fiber device in accordance with an exampleembodiment.

FIG. 2 is a cross-sectional diagram of the preform body of FIG. 1 takenalong line 2-2.

FIG. 3 is a schematic block diagram of a system incorporating an opticalfiber device in accordance with an example embodiment.

FIGS. 4 and 5 are flow diagrams illustrating methods for making anoptical fiber device in accordance with example embodiments.

FIG. 6 is a cross-sectional diagram of another embodiment of the preformbody of FIG. 2.

FIG. 7 is a front view of another 3D-printed preform body for use informing an optical fiber device in accordance with an exampleembodiment.

FIG. 8 is a cross-sectional diagram of the optical fiber device of FIG.3.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present description is made with reference to the accompanyingdrawings, in which exemplary embodiments are shown. However, manydifferent embodiments may be used, and thus the description should notbe construed as limited to the particular embodiments set forth herein.Rather, these embodiments are provided so that this disclosure will bethorough and complete. Like numbers refer to like elements throughout,and prime notation is used to indicate similar elements in differentembodiments.

Referring initially to FIGS. 1-3, a preform body for use in forming anoptical fiber device 31 is first described. By way of background,current optical fibers work relatively well for transporting visiblelight over long distances. However, such optical fibers may be limitedin their ability to carry other optical wavelengths, such as ultraviolet(UV) wavelengths, due to the above-described defects in typical opticalfibers. That is, while the defects are relatively benign with respect tovisible light, the defects interact with UV photons, by way of examplethe number of UV photons transported all the way through the fiber couldbe decreased due to the defects, and may cause premature failure in suchfibers.

One application where UV fibers are important is in quantum computing.However, current UV fiber technology is problematic in terms ofscalability, i.e. transporting photons over km-equivalents with highfidelity. Moreover, UV fibers have undesirably short lifetimes, althoughthey are still important enablers for quantum computing.

Another application where the drawbacks associated with current UVfibers is problematic is UV photolithography, such as for semiconductordevice fabrication. In such applications, beam stability is importantfor reaching the submicron feature sizes needed to continue reducingdevice sizes along Moore's law. However, a UV source generates asignificant amount of heat. However, the associated cooling mechanismsused to dissipate this heat also undesirably transferresolution-limiting vibrations into the beam forming optics because ofthe direct connection between the UV source and the optical receiver.

Still another application where the drawbacks of conventional UV fibersbecomes apparent is in power-over-fiber applications. Current fiberdesigns are power limited due to their inability to dissipate thermalenergy within the fibers. Yet, conventional copper power cables aregenerally unacceptable in terms of their size, weight and power (SWaP),as well as their relatively high signal losses.

The preform body 30 may advantageously be generated using a 3D printerwith an optical material, such as silicon carbide (as well assiliconized-silicon carbide), borosilicate glass, fused silica, dopedglasses, toughened or tempered glasses, and/or aluminum oxide, forexample. In some applications, other materials such as polymers orceramics may be used as well as optical materials.

In the illustrated example, the preform body 30 has a 3D pattern ofvoids therein defining a 3D lattice. More particularly, the illustrated3D lattice and voids 32 are defined by a plurality of strands 33 formedout of the optical material (or a plurality of different opticalmaterials in some embodiments). In this example, some of the voids 32open outwardly along a side of the preform body 30. Furthermore, theoptical strands 33 are intersecting and counter-rotating helical strandsin the present embodiment, although other geometries may also be used.Moreover, strands need not be used in all embodiments to define the 3Dlattice structure.

A communications system 39 is shown in FIG. 3 in which the optical fiberdevice 31 is coupled between one or more optical sources 36 and one ormore optical receivers 37. As noted above, the optical receiver(s) 37may be associated with a photolithography device, a quantum computingdevice, or an optical receiver for digital communications orpower-over-fiber applications, for example, as will be discussed furtherbelow.

By using a 3D-printed preform body 30, desired preform structures mayadvantageously be fabricated at a scale that is possible with currenttechnology (i.e., current 3D printing technology). This also allows forthe use of numerous different shapes in additional to thecylindrical/helical preform body 30, including squares and star shapes(e.g., a five- or six-pointed star). Another example geometry is aspherical preform body 130 seen in FIG. 7 which includes optical strands133. Such geometries may advantageously provide advantages incommunication applications, in that they allow for twisted light pairs,which advantageously increases light transmission to allow fortransmission over longer distances. That is, the use of twisted lightpairs increases the orbital angular momentum states, which do notinterface with one another. Also, by varying the thickness of thestrands 33 or portions of the preform body 30, this may alsoadvantageously twist the light, allowing a large number of twisted beamsto be transported down the same fiber, as will be appreciated by thoseskilled in the art.

Current optical fibers are typically aperiodic. Using the preform body30, an optical fiber 31 may be created which is periodic, or which has asingle pitch in the same direction, enabling the creation of twistedlight.

In addition to providing for twisted light beams, the optical fiber 31also advantageously allows for summed and difference beam outputs.Respective optical sources 36 may be coupled to respective strands 33within the optical fiber 31 in some embodiments. In other embodiments,some of the optical strands 33 may not have an optical source 36 coupledto them. That is, light may be sent down each of the optical strands 33,or down only selective ones of the optical strands. This mayadvantageously be used to modulate the phase, amplitude, polarizationand/or differences between light beams, depending on the configurationused. Furthermore, adjusting the thicknesses of the strands 33 and theirrespective pitches may advantageously be used to adjust the mode fieldof the optical fiber device 31 to make a large effective fiber, as willbe appreciated by those skilled in the art.

Referring additionally to the flow diagrams 60, 60′ of FIGS. 4 and 5, amethod for making an optical fiber device 31 from the preform body 30 isnow described. Beginning at Block 61 (or Block 61′), the process beginswith using a 3D printer to generate the preform body 30 having a 3Dpattern of voids defining a 3D lattice therein, as discussed above, atBlock 61 (or Block 61′). The method further illustratively includesdrawing the preform body to form the optical fiber device 31, at Block63 (or Block 63′), as will be discussed further below.

In the example embodiment illustrated in FIG. 5, a further step ofcoating one or more portions of the preform body 30 with a differentmaterial than the optical material is performed prior to drawing, atBlock 65′. In accordance with one example implementation, the method mayfurther include electroplating at least a portion of the preform body 30prior to drawing with a material that will pull with the preform bodyduring drawing. By way of example, gold (Au) stretches well and mayaccordingly be applied (e.g., by electroplating) as a “cladding” beforepulling. One advantage of this approach is that an electric field may beapplied through the gold (or other suitable metal) during the pullingprocess. Furthermore, different strands may be selectively coated tochange the polarization, etc., of the optical fiber 31. For example,coating every other optical strand may provide an oscillatingpolarization. Sputtering is another way to coat selective areas of thepreform body 30, which will change the total internalreflection/intensity in these areas. It should be noted that in someembodiments a coating or cladding may instead (or additionally) beapplied to the optical fiber 31 after it is drawn. The methods of FIGS.4 and 5 illustratively conclude at Blocks 64, 64′.

Generally speaking, the preform body 30 will be drawn in such a way asto retain the 3D pattern of voids therein in the final optical fiberdevice. That is, while the cross-sectional dimensions of the preformbody 30 will change as it is drawn down into the much thinner opticalfiber device 31, the general shape or geometry of the lattice and voids32 may be preserved although greatly elongated. A cross-sectional viewof the optical fiber device 31 is shown in FIG. 8. It should be notedthat in other embodiments, preforms may be used which do not resemblethe final drawn structure. For example, a process similar to an expandedmetal (exmet) process may be used in which the final drawn fiber doesnot resemble the preform.

In some embodiments, the preform body 30 may be drawn along an opticalaxis 34 of the preform body 30 (FIG. 1). However, one particularadvantage of using a 3D-printed preform body 30 is that this allows fordifferent types of pulls or drawing than are possible with conventionalfiber preforms. That is, in some embodiments the preform body 30 may bedrawn in a direction offset with respect to the optical axis 34 of thepreform body 30 or optical fiber 31. In another example, the preformbody 30 may be drawn in both axial and radial directions with respect tothe optical axis 34. By way of example, the preform body 30 may have asize in a range of about 1 to 2 feet in length, and an outer diameter ina range of 1 to 2 inches, although other dimensions may be used indifferent embodiments. Such a preform body 30 may be drawn down to anoptical fiber 31 of a kilometer in length or more in some embodiments.

Referring additionally to FIG. 6, in another example implementation ofthe preform body 30′, a conductive (e.g., metal) strand 35′ isincorporated along with the optical strands 33′. That is, one or moremetal strands 35′ are printed by the 3D printer along with the opticalstrands 33′. In the illustrated example, there is a single metal strand35′ which runs down the middle (i.e., along the optical axis) of thepreform body 30′, although the position of the metal strand(s) may bedifferent in different embodiments. The metal strand(s) 35′ may alsotake the same shape as the optical strands 33′ (e.g., helical).Moreover, in some embodiments strands do not have to be used in formingthe preform body 30′. That is, it may be a solid or semi-solid body withmetal traces extending therethrough like a via. One example materialwhich may be used for the strands 35′ is tungsten, although othersuitable conductive materials may be used in different embodiments.

Including one or more conductive strands 35′ in the preform body 30′provides certain advantages. One is that this allows for the creation ofan electric field in the optical fiber device 31′ that can affect lightphotons as desired. Another advantage is that conductive strands 35′ mayadvantageously be used to heat the preform body 30′ from the insideduring the drawing process (Block 63′), in addition to (or instead of)from the outside. That is, typical optical fiber preforms are simplyheated from the outside and drawn into the final fiber shape. Yet, thepreform body 30′ with the conductive strand(s) 35′ (or other conductivematerial arrangement within the preform body) advantageously allows formore uniform or even heating during drawing, and this uniform thermalgradient may advantageously result in a significant reduction in defectsduring the drawing process.

It should be noted that the cross-section of the preform body 30′changes as it is drawn. As a result, in those embodiments whichincorporate one or more conductive strands 33′ to which a current isapplied during the drawing process, the current applied may be scaledaccordingly to account for the increased resistance of the conductivestrand and avoid excessive heat.

Because the optical fibers 33 made in accordance with the presentdisclosure may have less defects and are able to transport UV light overlonger distances and with a longer service life, this may advantageouslyallow the optical (UV) source(s) 36 to be positioned farther away fromthe receiver(s) 37 in applications such as photolithography. As aresult, the optical receiver(s) 37 will advantageously be subjected toless of the heat and vibration associated with the source(s) 36, asdiscussed above.

For UV fibers, it is generally desirable to limit the amount ofinteraction between the UV light and glass, as the UV light breaks downsuch materials over time. As such, in some embodiments hollow coreoptical strands 33 may be used to provide less surface area for the UVlight to interact with the optical material.

It should be noted that while the above examples discuss the use of theoptical fiber 31 for UV applications, the optical fibers created inaccordance with the techniques described herein may advantageously beused for different optical wavelengths and spectrums including visiblelight, millimeter wave, X-ray, and THz wavelengths, for example.Accordingly, the optical fiber device 31 may advantageously be used torelatively inexpensively transport photons over many thousands ofwavelengths with fully customizable propagation characteristics.

The above-described approach advantageously harnesses the power ofadditive manufacturing to enable new uses and applications for opticalfiber devices providing enhanced performance and robustness. Forexample, this allows for the manufacture of UV fibers with significantlylonger lifetimes than are currently unattainable with conventionalapproaches. More particularly, the 3D-printed complex structures mayadvantageously enable photon guiding/interaction with a broader range ofoutput photon beam properties, and in applications where current opticalfibers are unsuitable. Moreover, this approach also enables thefabrication of previously impossible/unexplored 2D and 3D geometries.

As noted above, the approach described herein allows for 3D-printing ofcomplex structures from one or more materials that undergo zero tomultiple post-processing steps to produce a device that enablesbroadband (UV to microwave) photons to interact with each other and/orbe guided over several thousand wavelengths to a remote location.Furthermore, additively manufacturing glass preforms, instead of manualassembly from solid or hollow capillaries, advantageously enables forthe use of multiple different materials inside complex structures

Many modifications and other embodiments will come to the mind of oneskilled in the art having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it isunderstood that the disclosure is not to be limited to the specificembodiments disclosed, and that modifications and embodiments areintended to be included within the scope of the appended claims.

1-32. (canceled)
 33. An optical fiber preform comprising: a preform bodyto be drawn into a fiber optic device and comprising an opticalmaterial; the preform body comprising a plurality of helical strandshaving a three-dimensional (3D) pattern of voids therein defining a 3Dlattice.
 34. The optical fiber preform of claim 33 wherein the pluralityof helical strands comprises a plurality of counter-rotating, helicalstrands.
 35. The optical fiber preform of claim 33 wherein the pluralityof helical strands comprises a plurality of intersecting,counter-rotating, helical strands.
 36. The optical fiber preform ofclaim 33 comprising a coating on at least a portion of the preform bodycomprising a different material than the optical material.
 37. Theoptical fiber preform of claim 36 wherein the coating comprises anelectroplated coating.
 38. The optical fiber preform of claim 36 whereinthe coating comprises gold.
 39. The optical fiber preform of claim 33wherein at least one of the plurality of helical strands comprises ametal.
 40. The optical fiber preform of claim 39 wherein the metalcomprises tungsten.
 41. The optical fiber preform of claim 33 whereinthe optical material comprises at least one of silicon carbide andaluminum oxide.
 42. The optical fiber preform of claim 33 wherein thepreform body has an elongate shape.
 43. An optical fiber preformcomprising: a preform body to be drawn into a fiber optic device andcomprising an optical material; the preform body comprising a pluralityof strands defining a three-dimensional (3D) lattice with a 3D patternof voids therein, and at least some of the voids opening outwardly alonga side of the preform body.
 44. The optical fiber preform of claim 43wherein the plurality of strands comprises a plurality of helicalstrands.
 45. The optical fiber preform of claim 44 wherein the pluralityof helical strands comprises a plurality of counter-rotating, helicalstrands.
 46. The optical fiber preform of claim 44 wherein the pluralityof helical strands comprises a plurality of intersecting,counter-rotating, helical strands.
 47. The optical fiber preform ofclaim 43 comprising a coating on at least a portion of the preform bodycomprising a different material than the optical material.
 48. Theoptical fiber preform of claim 47 wherein the coating comprises anelectroplated coating.
 49. The optical fiber preform of claim 47 whereinthe coating comprises gold.
 50. The optical fiber preform of claim 43wherein at least one of the plurality of strands comprises a metal. 51.The optical fiber preform of claim 50 wherein the metal comprisestungsten.
 52. The optical fiber preform of claim 43 wherein the opticalmaterial comprises at least one of silicon carbide and aluminum oxide.53. The optical fiber preform of claim 43 wherein the preform body hasan elongate shape.
 54. An optical fiber preform comprising: a preformbody to be drawn into a fiber optic device and comprising an opticalmaterial; the preform body comprising a plurality of strands having athree-dimensional (3D) pattern of voids therein defining a 3D lattice;and a coating on at least a portion of the preform body comprising adifferent material than the optical material.
 55. The optical fiberpreform of claim 54 wherein the coating comprises an electroplatedcoating.
 56. The optical fiber preform of claim 54 wherein the coatingcomprises gold.
 57. The optical fiber preform of claim 54 wherein atleast one of the plurality of strands comprises a metal.
 58. The opticalfiber preform of claim 57 wherein the metal comprises tungsten.
 59. Theoptical fiber preform of claim 54 wherein the optical material comprisesat least one of silicon carbide and aluminum oxide.
 60. The opticalfiber preform of claim 54 wherein the preform body has an elongateshape.